St. John’s University has sold its 170-acre waterfront campus in Oakdale to a private, nonprofit international education group for $22.5 million, officials of the Queens-based school announced Tuesday.

Amity Education Group, which operates Amity University, one of the largest multi-campus colleges in India, purchased the property and will assume control of the land immediately.

Chancellor Aseem Chauhan said the acquisition would allow Amity to offer its existing international students an opportunity to study and live in New York.

“We believe in experiential learning, and students should have a global experience and live in different parts of the world for short-term programs,” Chauhan said in an interview. “It’s a beautiful campus and a great facility. It’s a peaceful setting and also nearby to one of the greatest cities in the world.”

The state Board of Regents must grant Amity authorization to operate a college in New York. The purchase of property — even property previously used as a college — does not mean that Amity can operate a college without Regents authorization, according to state education officials.

Amity Education Group says it has more than 150,000 students from preschool to the Ph.D. level in India, Dubai, China, Great Britain, Mauritius, Singapore and South Africa, with plans to establish campuses in 25 countries.

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The sales agreement allows St. John’s to lease space and to continue offering its academic programs there through June, St. John’s officials said in a statement.

“It’s a very big piece of property and we’ve had a lot of success there,” said St. John’s spokesman Dominic Scianna, adding that “it is the right time to sell and look for a new space so we can continue to serve our Long Island students.”

More than 220 students are enrolled in graduate programs in education and liberal arts at the Oakdale campus.

St. John’s, one of the largest and oldest Catholic institutions of higher education in the country, has about 20,000 students. The main campus is in Jamaica Estates.

Amity officials, who were on the Oakdale property Tuesday, said it was too early to release the details of their academic programming before the plans have gained regulatory approvals.

The group’s higher education component, Amity University, was among 17 institutions that submitted proposals to New York City in 2011 as part of then-Mayor Michael Bloomberg’s search for a new engineering and applied sciences campus on Roosevelt Island.

St. John’s bought the Oakdale property for $14.3 million in 1999, according to Suffolk County property records. The university purchased it from the LaSalle Christian Brothers, who operated LaSalle Military Academy there for more than 75 years.

The site was the estate of Frederick Bourne, president of Singer Sewing Machine Co., from 1889 to 1905.

The property, at 500 Montauk Hwy., consists of 11 buildings with an extensive lawn and sweeping views of the Great South Bay. The main structure is the Georgian-style Bourne Mansion, built in 1897.

The mansion is rented out for weddings and other large private parties through the Lessing’s Hospitality Group, a family-owned firm in Great River.

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Chief operating officer Michael Lessing said the sale does not affect the agreement with his catering company to hold events there.

The commercial real estate firm Cushman & Wakefield brokered the sale, officials said.

St. John’s officials put the property on the market in January and signed a sales contract with Amity University officials in June. The transaction closed on Tuesday.

Scianna declined to disclose the asking price. He also would not say where university officials may move St. John’s academic programs on Long Island.

In July 2013, the university sold its Manhattan location at 101 Murray St. for $223 million. The university continues to lease space in another building, 101 Astor Place in the East Village, Scianna said.

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In addition to Manhattan and Oakdale, St. John’s operates satellite campuses on Staten Island, and abroad, in Paris and Rome.